1. Field of the Invention
This invention relates to photoreceptors for electrophotographic printing. Particularly, this invention relates to a photoreceptor belt in combination with a cylindrical mandrel. More particularly, this invention relates to a photoreceptor belt removably attached to a cylindrical mandrel.
The photoreceptor design of the invention is particularly well suited to replace the current belt or drum photoreceptor designs of electrophotographic printing machines. The current invention will extend the life of the photoreceptor, increase ease of replacement, and reduce the number of complex parts required in a photoreceptor assembly.
2. Description of the Art
In an electrophotographic mono-color printing machine, a photoconductive member is charged to a substantially uniform potential. The charged portion of the photoconductive member is exposed to a light reflected original document image. Exposure of the charged photoconductive member selectively dissipates the charge in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document being reproduced. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing it into contact with toner. The toner image on the photoconductive member is subsequently transferred to a copy sheet. The copy sheet is heated to permanently affix the toner image. Multicolor electrophotographic printing is substantially identical, although more complex than the mono-color printing process. Cyclic and tandem color copying processes dominate the art of color printing.
In a cyclic multicolor printing process, successive latent images corresponding to different colors are recorded on the photoconductive member during each cycle. Accordingly, one photoconductive member is required in this type of machine. The photoconductive member is used repetitively for each color/cycle. Each single color electrostatic latent image is developed with toner of a color complementary thereto. This process is repeated a plurality of cycles for the different colors in an image and the respective complementary color toner. Each single color toner image is transferred to the copy sheet and superimposed with the prior toner image. This creates a multilayered toner image on the copy sheet. Thereafter, the multilayered toner image is permanently affixed to the copy sheet creating a color copy. The primary attributes of a cyclic printing machine are its relatively low number of parts and its low cost. U.S. Pat. No. 4,583,991, herein incorporated by reference, describes a cyclic printing machine in which a sheet moves in recirculated path and successive color toners images are transferred thereto.
A typical tandem printing machine uses multiple printing engines to transfer, in one cycle, different colored toner images directly to a sheet or to an intermediate for subsequent transfer to the sheet. Printing rate is the primary advantage of a tandem machine since all colors are printed in one cycle. However, the complex equipment of a tandem machine leads to a higher cost.
U.S. Pat. Nos. 4,796,050 and 4,803,518, herein incorporated by reference, disclose tandem printing machines having a plurality of photoconductive drums arranged such that color separated light images of an original document are recorded thereon as electrostatic latent images. The latent images are developed into visible color images. A conveyor advances a sheet past each photoconductive drum. Visible color images are transferred from each photoconductive drum to the sheet.
Both cyclic and tandem printing machines can use drum or belt type photoreceptors. Problems are encountered in the use of photoconductive belts because of their reliability, the life of the belt modules, and their difficulty of replacement. In addition, belt modules often experience inboard/outboard travel or even travel in the direction of paper flow. Drum photoconductors are troublesome because of their high cost and their difficulty to replace.